/*
Copyright 2016 Gravitational, Inc.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Package defaults contains default constants set in various parts of
// teleport codebase
package defaults

import (
	"fmt"
	"time"

	"github.com/gravitational/teleport/lib/limiter"
	"github.com/gravitational/teleport/lib/utils"
)

// Default port numbers used by all teleport tools
const (
	// Web UI over HTTP(s)
	HTTPListenPort = 3080

	// When running in "SSH Server" mode behind a proxy, this
	// listening port will be used to connect users to:
	SSHServerListenPort = 3022

	// When running in "SSH Proxy" role this port will be used to
	// accept incoming client connections and proxy them to SSHServerListenPort of
	// one of many SSH nodes
	SSHProxyListenPort = 3023

	// When running in "SSH Proxy" role this port will be used for incoming
	// connections from SSH nodes who wish to use "reverse tunnell" (when they
	// run behind an environment/firewall which only allows outgoing connections)
	SSHProxyTunnelListenPort = 3024

	// When running as a "SSH Proxy" this port will be used to
	// serve auth requests.
	AuthListenPort = 3025

	// Default DB to use for persisting state. Another options is "etcd"
	BackendType = "bolt"

	// BackendDir is a default backend subdirectory
	BackendDir = "backend"

	// BackendPath is a default backend path parameter
	BackendPath = "path"

	// Name of events bolt database file stored in DataDir
	EventsBoltFile = "events.db"

	// By default SSH server (and SSH proxy) will bind to this IP
	BindIP = "0.0.0.0"

	// By default all users use /bin/bash
	DefaultShell = "/bin/bash"

	// CacheTTL is a default cache TTL for persistent node cache
	CacheTTL = 20 * time.Hour

	// RecentCacheTTL is a default cache TTL for recently accessed items
	RecentCacheTTL = 2 * time.Second

	// InviteTokenTTL sets the lifespan of tokens used for adding nodes and users
	// to a cluster
	InviteTokenTTL = 15 * time.Minute

	// DefaultDialTimeout is a default TCP dial timeout we set for our
	// connection attempts
	DefaultDialTimeout = 30 * time.Second

	// HTTPMaxIdleConns is the max idle connections across all hosts.
	HTTPMaxIdleConns = 2000

	// HTTPMaxIdleConnsPerHost is the max idle connections per-host.
	HTTPMaxIdleConnsPerHost = 1000

	// HTTPIdleTimeout is a default timeout for idle HTTP connections
	HTTPIdleTimeout = 30 * time.Second

	// DefaultThrottleTimeout is a timemout used to throttle failed auth servers
	DefaultThrottleTimeout = 10 * time.Second

	// DefaultIdleConnectionDuration indicates for how long Teleport will hold
	// the SSH connection open if there are no reads/writes happening over it.
	// 15 minutes default is compliant with PCI DSS standards
	DefaultIdleConnectionDuration = 15 * time.Minute

	// ShutdownPollPeriod is a polling period for graceful shutdowns of SSH servers
	ShutdownPollPeriod = 500 * time.Millisecond

	// ReadHeadersTimeout is a default TCP timeout when we wait
	// for the response headers to arrive
	ReadHeadersTimeout = time.Second

	// SignupTokenTTL is a default TTL for a web signup one time token
	SignupTokenTTL = time.Hour

	// MaxSignupTokenTTL is a maximum TTL for a web signup one time token
	// clients can reduce this time, not increase it
	MaxSignupTokenTTL = 48 * time.Hour

	// ProvisioningTokenTTL is a the default TTL for server provisioning
	// tokens. When a user generates a token without an explicit TTL, this
	// value is used.
	ProvisioningTokenTTL = 30 * time.Minute

	// HOTPFirstTokensRange is amount of lookahead tokens we remember
	// for sync purposes
	HOTPFirstTokensRange = 4

	// HOTPTokenDigits is the number of digits in each token
	HOTPTokenDigits = 6

	// MinPasswordLength is minimum password length
	MinPasswordLength = 6

	// MaxPasswordLength is maximum password length (for sanity)
	MaxPasswordLength = 128

	// IterationLimit is a default limit if it's not set
	IterationLimit = 100

	// MaxIterationLimit is max iteration limit
	MaxIterationLimit = 1000

	// EventsIterationLimit is a default limit if it's not set for events
	EventsIterationLimit = 500

	// EventsIterationLimit is max iteration limit for events
	EventsMaxIterationLimit = 10000

	// ActiveSessionTTL is a TTL when session is marked as inactive
	ActiveSessionTTL = 30 * time.Second

	// ActivePartyTTL is a TTL when party is marked as inactive
	ActivePartyTTL = 30 * time.Second

	// OIDCAuthRequestTTL is TTL of internally stored auth request created by client
	OIDCAuthRequestTTL = 10 * 60 * time.Second

	// SAMLAuthRequestTTL is TTL of internally stored auth request created by client
	SAMLAuthRequestTTL = 10 * 60 * time.Second

	// GithubAuthRequestTTL is TTL of internally stored Github auth request
	GithubAuthRequestTTL = 10 * 60 * time.Second

	// OAuth2TTL is the default TTL for objects created during OAuth 2.0 flow
	// such as web sessions, certificates or dynamically created users
	OAuth2TTL = 60 * 60 * time.Second // 1 hour

	// LogRotationPeriod defines how frequently to rotate the audit log file
	LogRotationPeriod = (time.Hour * 24)

	// UploaderScanPeriod is a default uploader scan period
	UploaderScanPeriod = 5 * time.Second

	// UploaderConcurrentUploads is a default number of concurrent
	UploaderConcurrentUploads = 10

	// MaxLoginAttempts sets the max. number of allowed failed login attempts
	// before a user account is locked for AccountLockInterval
	MaxLoginAttempts int = 5

	// AccountLockInterval defines a time interval during which a user account
	// is locked after MaxLoginAttempts
	AccountLockInterval = time.Duration(20 * time.Minute)

	// Namespace is default namespace
	Namespace = "default"

	// AttemptTTL is TTL for login attempt
	AttemptTTL = time.Minute * 30

	// AuditLogSessions is the default expected amount of concurrent sessions
	// supported by Audit logger, this number limits the possible
	// amount of simultaneously processes concurrent sessions by the
	// Audit log server, and 16K is OK for now
	AuditLogSessions = 16384

	// AccessPointCachedValues is the default maximum amount of cached values
	// in access point
	AccessPointCachedValues = 16384

	// AuditLogTimeFormat is the format for the timestamp on audit log files.
	AuditLogTimeFormat = "2006-01-02.15:04:05"

	// PlaybackRecycleTTL is the TTL for unpacked session playback files
	PlaybackRecycleTTL = 3 * time.Hour

	// WaitCopyTimeout is how long Teleport will wait for a session to finish
	// copying data from the PTY after "exit-status" has been received.
	WaitCopyTimeout = 5 * time.Second
)

var (
	// ReverseTunnelAgentHeartbeatPeriod is the period between agent heartbeat messages
	ReverseTunnelAgentHeartbeatPeriod = 5 * time.Second

	// ReverseTunnelOfflineThreshold is the threshold of missed heartbeats
	// after which we are going to declare the reverse tunnel offline
	ReverseTunnelOfflineThreshold = 5 * ReverseTunnelAgentHeartbeatPeriod

	// ServerHeartbeatTTL is a period between heartbeats
	// Median sleep time between node pings is this value / 2 + random
	// deviation added to this time to avoid lots of simultaneous
	// heartbeats coming to auth server
	ServerHeartbeatTTL = 90 * time.Second

	// AuthServersRefreshPeriod is a period for clients to refresh their
	// their stored list of auth servers
	AuthServersRefreshPeriod = 30 * time.Second

	// TerminalResizePeriod is how long tsh waits before updating the size of the
	// terminal window.
	TerminalResizePeriod = 2 * time.Second

	// SessionRefreshPeriod is how often session data is updated on the backend.
	// The web client polls this information about session to update the UI.
	//
	// TODO(klizhentas): All polling periods should go away once backend supports
	// events.
	SessionRefreshPeriod = 2 * time.Second

	// SessionIdlePeriod is the period of inactivity after which the
	// session will be considered idle
	SessionIdlePeriod = SessionRefreshPeriod * 10

	// NewtworkBackoffDuration is a standard backoff on network requests
	// usually is slow, e.g. once in 30 seconds
	NetworkBackoffDuration = time.Second * 30

	// NewtworkRetryDuration is a standard retry on network requests
	// to retry quickly, e.g. once in one second
	NetworkRetryDuration = time.Second

	// FastAttempts is the initial amount of fast retry attempts
	// before switching to slow mode
	FastAttempts = 10

	// ReportingPeriod is a period for reports in logs
	ReportingPeriod = 5 * time.Minute

	// HighResPollingPeriod is a default high resolution polling period
	HighResPollingPeriod = 10 * time.Second
)

// Default connection limits, they can be applied separately on any of the Teleport
// services (SSH, auth, proxy)
const (
	// Number of max. simultaneous connections to a service
	LimiterMaxConnections = 1000

	// Number of max. simultaneous connected users/logins
	LimiterMaxConcurrentUsers = 250
)

const (
	// HostCertCacheSize is the number of host certificates to cache at any moment.
	HostCertCacheSize = 4000

	// HostCertCacheTime is how long a certificate stays in the cache.
	HostCertCacheTime = 24 * time.Hour
)

const (
	// MinCertDuration specifies minimum duration of validity of issued cert
	MinCertDuration = time.Minute
	// MaxCertDuration limits maximum duration of validity of issued cert
	MaxCertDuration = 30 * time.Hour
	// CertDuration is a default certificate duration
	// 12 is default as it' longer than average working day (I hope so)
	CertDuration = 12 * time.Hour
	// RotationGracePeriod is a default rotation period for graceful
	// certificate rotations, by default to set to maximum allowed user
	// cert duration
	RotationGracePeriod = MaxCertDuration
)

// list of roles teleport service can run as:
const (
	// RoleNode is SSH stateless node
	RoleNode = "node"
	// RoleProxy is a stateless SSH access proxy (bastion)
	RoleProxy = "proxy"
	// RoleAuthService is authentication and authorization service,
	// the only stateful role in the system
	RoleAuthService = "auth"
)

var (
	// ConfigFilePath is default path to teleport config file
	ConfigFilePath = "/etc/teleport.yaml"

	// DataDir is where all mutable data is stored (user keys, recorded sessions,
	// registered SSH servers, etc):
	DataDir = "/var/lib/teleport"

	// StartRoles is default roles teleport assumes when started via 'start' command
	StartRoles = []string{RoleProxy, RoleNode, RoleAuthService}

	// ETCDPrefix is default key in ETCD clustered configurations
	ETCDPrefix = "/teleport"

	// ConfigEnvar is a name of teleport's configuration environment variable
	ConfigEnvar = "TELEPORT_CONFIG"

	// LicenseFile is the default name of the license file
	LicenseFile = "license.pem"

	// CACertFile is the default name of the certificate authority file to watch
	CACertFile = "ca.cert"
)

const (
	// ServiceName is the default PAM policy to use if one is not passed in
	// configuration.
	ServiceName = "sshd"
)

const (
	initError = "failure initializing default values"
)

const (
	// This is hardcoded in the U2F library
	U2FChallengeTimeout = 5 * time.Minute
)

// TLS constants for Web Proxy HTTPS connection
const (
	// path to a self-signed TLS PRIVATE key file for HTTPS connection for the web proxy
	SelfSignedKeyPath = "webproxy_key.pem"
	// path to a self-signed TLS PUBLIC key file for HTTPS connection for the web proxy
	SelfSignedPubPath = "webproxy_pub.pem"
	// path to a self-signed TLS cert file for HTTPS connection for the web proxy
	SelfSignedCertPath = "webproxy_cert.pem"
)

// ConfigureLimiter assigns the default parameters to a connection throttler (AKA limiter)
func ConfigureLimiter(lc *limiter.LimiterConfig) {
	lc.MaxConnections = LimiterMaxConnections
	lc.MaxNumberOfUsers = LimiterMaxConcurrentUsers
}

// AuthListenAddr returns the default listening address for the Auth service
func AuthListenAddr() *utils.NetAddr {
	return makeAddr(BindIP, AuthListenPort)
}

// AuthConnectAddr returns the default address to search for auth. service on
func AuthConnectAddr() *utils.NetAddr {
	return makeAddr("127.0.0.1", AuthListenPort)
}

// ProxyListenAddr returns the default listening address for the SSH Proxy service
func ProxyListenAddr() *utils.NetAddr {
	return makeAddr(BindIP, SSHProxyListenPort)
}

// ProxyWebListenAddr returns the default listening address for the Web-based SSH Proxy service
func ProxyWebListenAddr() *utils.NetAddr {
	return makeAddr(BindIP, HTTPListenPort)
}

// SSHServerListenAddr returns the default listening address for the Web-based SSH Proxy service
func SSHServerListenAddr() *utils.NetAddr {
	return makeAddr(BindIP, SSHServerListenPort)
}

// ReverseTunnellListenAddr returns the default listening address for the SSH Proxy service used
// by the SSH nodes to establish proxy<->ssh_node connection from behind a firewall which
// blocks inbound connecions to ssh_nodes
func ReverseTunnellListenAddr() *utils.NetAddr {
	return makeAddr(BindIP, SSHProxyTunnelListenPort)
}

func makeAddr(host string, port int16) *utils.NetAddr {
	addrSpec := fmt.Sprintf("tcp://%s:%d", host, port)
	retval, err := utils.ParseAddr(addrSpec)
	if err != nil {
		panic(fmt.Sprintf("%s: error parsing '%v'", initError, addrSpec))
	}
	return retval
}

const (
	// RSABits is the default RSA bits for the private key
	RSABits = 2048

	// CATTL is a default lifetime of a CA certificate
	CATTL = time.Hour * 24 * 365 * 10
)

const (
	// AuditEnvelopeType is sending a audit event over the websocket to the web client.
	AuditEnvelopeType = "a"

	// RawEnvelopeType is sending raw terminal bytes over the websocket to the web
	// client.
	RawEnvelopeType = "r"

	// ResizeRequestEnvelopeType is receiving a resize request.
	ResizeRequestEnvelopeType = "r.r"
)

// The following are cryptographic primitives Teleport does not support in
// it's default configuration.
const (
	DiffieHellmanGroup14SHA1 = "diffie-hellman-group14-sha1"
	DiffieHellmanGroup1SHA1  = "diffie-hellman-group1-sha1"
	HMACSHA1                 = "hmac-sha1"
	HMACSHA196               = "hmac-sha1-96"
)
